Organic compounds -- part of the class 532-570 series – Organic compounds – Isocyanate esters
Reexamination Certificate
2007-04-17
2007-04-17
Parsa, J. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Isocyanate esters
C560S333000, C560S352000
Reexamination Certificate
active
11048667
ABSTRACT:
The invention relates to a process for the production of di- and polyisocyanates of the diphenylmethane series and mixtures thereof, in which aniline and formaldehyde are reacted in the presence of an acid catalyst to form di- and polyamines of the diphenylmethane series; the di- and polyamines of the diphenylmethane series are phosgenated, optionally in the presence of a solvent, to obtain a crude di- and polyisocyanate; from the crude di- and polyisocyanate, at least one fraction containing at least 5 wt. % 3-ring and multi-ring MDI and at least one fraction containing at least 95 wt. % 2-ring MDI are separated by distillation, and the acidities of the fraction containing at least 5 wt. % 3-ring MDI and multi-ring MDI, and/or the fraction containing at least 95 wt. % 2-ring MDI are determined analytically; and an acidic compound is added to the fraction containing at least 5 wt. % 3-ring MDI and multi-ring MDI, and/or the fraction containing at least 95 wt. % 2-ring MDI, so that the desired acidity is achieved.
REFERENCES:
patent: 3155699 (1964-11-01), Powers
patent: 4414074 (1983-11-01), Ellendt et al.
patent: 6576788 (2003-06-01), Penzel et al.
patent: 2004/0171869 (2004-09-01), Reif et al.
Echterhoff Ralf
Liman Ulrich
Müller Heinz-Herbert
Vieler Robert
Bayer Materialscience Aktiengesellschaft
Brown N. Denise
Gil Joseph C.
Parsa J.
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